don't colossi with thermal lance outrange marines?
forcefield + that^ or psi storm = r.i.p. marines (?)
Yes, they do I believe new range is 9 instead of original 6, marines are 5. thing is, the idea of mass marines is to 1 rax exp then keep harassing to prevent your opponent from being able to get colossi or limit max number to 1. Check the strategy part on TL for details